Bob with NCM 1994 coupe problems
Thread Starter
Instructor
Joined: Jul 2009
Posts: 242
Likes: 7
From: Bowling Green KY
Bob with NCM 1994 coupe problems
This is a mystery that is confounding me that I hope someone here can give me some insight on.
About 6 months ago, my 1994 coupe died while waiting at a light, then every few days it would do it again, usually while slowing down or idle. It was almost like there was a cutoff switch. The only problem I knew I had was with a vacuum leak at the throttle body cover so I fixed that, but still had the problem
Then I changed the coil and ignition control module.
Still died.
Then I changed the fuel pump relay and fuel pressure regulator.
Still died.
Finally, I rigged a fuel pressure gauge to it and carried a spark plug with me. The next time it died I popped the hood, pulled a spark plug wire, put it in and set to where I could see it and the fuel pressure. I had plenty of fuel pressure but no spark.
So I changed the opti, water pump, thermostat, and coolant temperature sensor.
Now it usually takes a couple of attempts to get it to start, and the water temp reading starts out at 142 and never changes. The hoses on both sides of the pump get hot. Thinking my sensor was bad, I replaced it with another one with no luck.
Update: I ran the codes and got H15 which led me to a thread here that is pointing to the coolant temp sensor still. Perhaps the two I have are both duds. I'll order one from somewhere else and see if that helps.
In the meantime, I don't see how that would affect my other problem. Any thoughts or advice other than selling it?
About 6 months ago, my 1994 coupe died while waiting at a light, then every few days it would do it again, usually while slowing down or idle. It was almost like there was a cutoff switch. The only problem I knew I had was with a vacuum leak at the throttle body cover so I fixed that, but still had the problem
Then I changed the coil and ignition control module.
Still died.
Then I changed the fuel pump relay and fuel pressure regulator.
Still died.
Finally, I rigged a fuel pressure gauge to it and carried a spark plug with me. The next time it died I popped the hood, pulled a spark plug wire, put it in and set to where I could see it and the fuel pressure. I had plenty of fuel pressure but no spark.
So I changed the opti, water pump, thermostat, and coolant temperature sensor.
Now it usually takes a couple of attempts to get it to start, and the water temp reading starts out at 142 and never changes. The hoses on both sides of the pump get hot. Thinking my sensor was bad, I replaced it with another one with no luck.
Update: I ran the codes and got H15 which led me to a thread here that is pointing to the coolant temp sensor still. Perhaps the two I have are both duds. I'll order one from somewhere else and see if that helps.
In the meantime, I don't see how that would affect my other problem. Any thoughts or advice other than selling it?
Last edited by Bob2.0; May 28, 2019 at 08:33 PM.
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
Original problem sounds like carbon build up in throttle body and inoperative IAC.
CTS will cause startling problems. CTS is in water pump possibly damaged connector during previous repairs.
CTS will cause startling problems. CTS is in water pump possibly damaged connector during previous repairs.
Thread Starter
Instructor
Joined: Jul 2009
Posts: 242
Likes: 7
From: Bowling Green KY
Thank you for the reply and the information.
It turned out that the new Duralast CTSs were both bad. I bought an AC Delco, and it worked perfectly.
I've cleaned the Throttle body, but will look closer at the IAC now.
One new thing I discovered today though, was that the wiring leading to the connector on the MAF needs replacing. When I took hold of the wires to move them out of the way, the car stalled. I'm guessing there is a short in there that might have been the problem all along.
More to come...
It turned out that the new Duralast CTSs were both bad. I bought an AC Delco, and it worked perfectly.
I've cleaned the Throttle body, but will look closer at the IAC now.
One new thing I discovered today though, was that the wiring leading to the connector on the MAF needs replacing. When I took hold of the wires to move them out of the way, the car stalled. I'm guessing there is a short in there that might have been the problem all along.
More to come...
